openssl: add option to provide the openssl library path

Add a new variable to have the directory that contains the openssl
libraries needed for xtest. The build system will look for the
needed libraries specified in this variable during the linking of
xtest.

Signed-off-by: Davidson Kumaresan <davidson.kumaresan@arm.com>

host/xtest/Makefile

@@ -40,7 +40,7 @@ endef
 WITH_OPENSSL ?= y
 ifeq ($(WITH_OPENSSL),y)
 CFLAGS += -DOPENSSL_FOUND=1 -DOPENSSL_API_COMPAT=10100
-LDFLAGS += -lcrypto
+LDFLAGS += -L$(OPENSSL_DIR)/lib -lcrypto
 endif #require OpenSSL
 
 srcs := regression_1000.c
@@ -107,6 +107,7 @@ CFLAGS += -I../supp_plugin/include
 CFLAGS += -I$(out-dir)/xtest
 
 CFLAGS += -I$(OPTEE_CLIENT_EXPORT)/include
+CFLAGS += -I$(OPENSSL_DIR)/include
 CFLAGS += -I$(TA_DEV_KIT_DIR)/host_include
 
 CFLAGS += -I../../ta/include